Terminal



S. E. PETERS TERMINAL Filed Oct. 24, 1952 I INVENTORI SAMUEL E. PETERSATTORNEYS:

United States Patent TERMINAL Samuel E. Peters, Racine, Wis., assignorto The Dumore Company, Racine, Wis., a corporation of WisconsinApplication October 24, 1952, Serial No. 316,621

3 Claims. (Cl. 339-456) This invention relates to a terminal foreffecting electrical connection with a brush holder or similar device.

The conventional brush holder includes a cylindrical brass sleeve withinwhich the brush is slidably mounted, suitable electrical connectionbeing provided between the sleeve and the brush proper. Electricalconnection between the field circuit of the motor and the brush sleeveis made by providing a terminal which surrounds the brass sleeve, and towhich the end of the field lead may be soldered or otherwise secured.

The characteristics that must be possessed by such terminal are first, avery secure mechanical connection must be made; and second, that goodelectrical contact be provided to avoid over-heating.

The mechanical requirements imposed on such a terminal are quite severedue to the fact that motors embodying this type of construction arefrequently incorporated in tools and appliances wherein the motor issubjected to severe vibration. Therefore, insofar as a secure mechanicalconnection is concerned, such a terminal must be able to withstand suchvibration without becoming loosened. quently replaced, it is desirableto provide a terminal which can easily be removed or applied to a brushholder, without the necessity of using special tools.

One type of terminal now in use comprises a metal ring which includes ascrew threaded device for drawing up the ring so as to provide goodelectrical and mechanical contact. The screw threaded device is alsoused to secure a terminal member to the ring in electrically conductingrelationship. The disadvantage of this screw and ring type of terminalis first; the matter of expense; second, removal and application requirethe use of a screw driver; and third, unless applied with care, thescrew may be come loosened, due to vibration.

To overcome the foregoing objections, various resilient or spring typesof terminals have been proposed which frictionally embrace the brasssleeve, thus eliminating the screw. For this purpose, the brass sleeveis generally provided with a groove to receive such a terminal. Thespring terminals heretofore used have been limited functionally by thefact that only a comparatively small contact area is provided, therebycausing heating and excessive voltage drop, and sometimes annealing ofthe terminal. Furthermore, in order to obtain a mechanical connectionwhich is comparable with that provided by the screw and ring type, ithas been necessary to make such resilient type terminals from a copperalloy wire of fairly heavy gauge with the result that some difficulty isencountered in applying the same to the brush holder, especially whenthe restricted space requirements are taken into consideration.

It is an object of the present invention to provide an improved springterminal which overcomes the aforementioned difficulties and objectionsto the terminals of the prior art.

It is a further object of the present invention to provide a springterminal which has a double wrap of spring,

Furthermore, since brush holders are frethereby giving greater contactarea than that provided by the single wrap spring terminals in the priorart, and also providing an improved mechanical gripping action.

A still further object of the present invention is to provide a doublewrap spring contact which is so formed as to prevent the twoconvolutions or turns from telescoping or overriding, since this wouldmaterially reduce the electrical contact area.

Still another object is to provide an improved spring contact which canbe easily snapped into or out of place on a brush holder without the useof tools. In this connection, I provide the terminal with asymmetrically disposed loop portion which can serve as a handle forconvenient manipulation. Due to the symmetrical disposition of the loop,the frictional grip will be maintained irrespective of thecircumferential position of the loop with respect to the brush holder,or of any force applied to the loop. In other words, the frictional gripwill be neither tightened or loosened due to any shift in the angularposition of the terminal with respect to the brush holder. The conductoris secured to the terminal at this loop portion.

Other objects, features and advantages will become apparent as thedescription proceeds.

With reference now to the drawings in which like reference numeralsdesignate like parts:

Fig. 1 is a view of a brush holder and terminal according to myinvention;

Fig. 2 is an end view of Fig. 1;

Fig. 3 is an enlarged view of the clip itself;

Fig. 4 is a view showing the manner in which the conductor is attachedto the terminal;

Fig. 5 is an edge view of Fig. 3;

Fig. 6 is a View showing the manner in which the terminal can bepositioned onto the brush holder; and

Figs. 7 and 8 are views, partially in section, showing the terminal asapplied to modified types of brush holders.

With reference now to Figs. 1 and 2, the reference numeral 10 designatesgenerally a brush holder which comprises a brass sleeve 11, a portion ofwhich is surrounded by an insulating sleeve 12. The brush, not shown, isdisposed within the sleeve 11. The terminal which surrounds the brasssleeve 11 in electrical conducting relationship therewith is designatedby the reference numeral 13. The exposed portion of the brass sleeve maybe provided with a shallowgroove 14 of a width to receive the terminal.

As shown in Fig. 2, a conductor 15 may be secured to the terminal 13 ata tab or loop portion 16.

As shown in Figs. 3 and 4, the terminal itself comprises a length ofwire which is formed into a helix of somewhat less than two turns. Thewire is formed from resilient stock, such as a Phosphor bronze orberyllium copper wire, No. 16 B & S gauge. The loop 16 is formed in theterminal at the mid-point of the length of wire from which the clip is:formed. Thus, the loop divides the terminal into two arm portions 17 and18, each of which is somewhat less than 360 in length. The end portionof each arm is bent up, as indicated by the reference numerals 19 and20.

There is thus provided a terminal which is easily expansible to theslight extent necessary to enable it to be snapped over the end of thebrush holder and into the groove 14.

The bent up ends 19 and 20 prevent the separate convolutions or turnsfrom telescoping upon each other or overriding, thus causing fullcontact to be maintained with the brush holder. Furthermore, the bent upends provide easier assembly and dis-assembly with the brush holder. Ifthe bent up ends were not. provided, there would be a sharp edge whichwould tend to bite into the brush holder, and which would catch on theend asym t pp n .Linstance,.theamount of ofiset can beanywhere betweenzeroz and substantially 60. degrees,: thereby. providing for each.arm.-alength ofsubstantially three hundred degrees or. more.

.;,snapped .in place.

surface of the brush holder as the terminal is being snapped into place.

Thus, the bending of the ends provides two symmetrit. eallysdisposedrounded, portions. 21 and 22 which bear against the sleeve. in.such a manner v that. the angular positionof .theaterminalawithrespect-to the sleeve can tIt.-,will be. observed that therounded end.portions 21 and-22 areofi'set from thecenter line of the U-shaped loopportion less than 90 degrees so that a full and action .can :take place.For

.Eig. 4-showshthe manner in which the bared end 24 As shown in Theapplication of the terminal to the brush holder is illustrated in Fig.6; one side of the terminal is first hooked over the edge of the groove;then finger pres- .sure applied to the opposite side of the terminalwill cause the same to expand sufiiciently so that it will be sure isapplied to the loop 16, and the terminal-will snap off of the brushholder without any difficulty.

Instead of a single double width groove 14, asshown inlliig. 1, thebrush holder may be provided with two separate parallel grooves 27 asshown in Fig. 7, or with a spiral groove 28 as shown in Fig. 8. Theparallel .groove-is as effective as the spiral groove due to the naturalbridging of the groove land by the loop of the :terminal.

Actually, the terminal herein shown provides good electrical contacteven though the brush holder is not grooved; I however, agroove ispreferable from the viewpoint of a secure. mechanical connection.

Various modifications-andchanges may be made in that embodiment of myinvention which has been shown and-described herein without departingfrom the spirit of the invention. as pointed out in the followingclaims.

I claim: 1. In combination, a brush holder having a grooved To removethe terminal, lateral pres- H portion adjacent one end, a springterminal disposed within said groove, and a conductor secured to saidterminal, said terminal comprising a resilient wire helix of slightlyless than two turns and having a symmetrically disposed loop dividingsaid helix into two symmetrically disposed arm portions each providingan independent gripping action, each arm portion being of a lengthsubstantially less than 360 so that each arm may be expanded solely byfieXure, whereby said spring terminal may be applied to said brushholder by slipping the same over the end of said brush holder in alateral direction, said conductor being twisted and soldered to saidloop, and said loop providing 'a handle for manipulation of said springterminal insaid lateral direction.

2. A brush holder terminal comprising a spring Wire helix of from oneand one-half to two turns, said helix being provided with asymmetrically disposed loop which dividesthe helix-into-twoarmportionsof from th'reefourths ofa. turn to one .turn each andeachproviding an independent gripping action, the'end portionsof saidarms being bent outwardly to prevent the turns from overriding one uponthe. other, and the portions adjacent. said bent endportionsconstituting symmetrically disposed roundedbearing portions.

3. A spring terminal for cooperation with the brush holder sleevevofamotor comprising a length of resilient wire having a U-shaped loopformed at substantially its mid-point, the two arms of said length ofwire each .being curved throughout substantially 300soas toprovide adouble wrap and each providing an independent gripping action, the endportions ofeach 0f saidarms being bent upwardly to prevent the free endfrom passing beneath the. adjacent convolution.

References Cited in the file of this patent UNITED STATES PATENTS1,557,111 Rutledge Oct. 13, 1925 1,606,506 Bushnell Nov. 9, 19261,865,207 Persons June 28, 1932 2,454,230 Stickney Nov. 16, 19482,602,105 'W'elch July 1, 1952 FOREIGN PATENTS 10,074/02 Great. BritainMay 1, 1902 242,391 Great Britain Mar. 12, 1925 434,825 France Dec. 7,1911 I 835,164 Germany Mar. 27,. 1952 504,922 Canada Aug; 10,1954

